Gen. Chem question from kaplan subject test 4

[allstardentist]

4. Which of the following, if added to a saturated aqueous
solution of NaCl, would most effectively reduce the
chloride ion concentration?
A. AgNO3
B. Ba(NO3)2
C. K2SO4
D. H2S
E. CH3COOH

Need some help on this problem. The answer is A. Can anyone please explain to me why this is the correct answer? Thanks.

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[allstardentist]

And also this problem...
25. Why is it more difficult to compress a liquid to a solid
than it is to compress a gas to a liquid?
A. van der Waals forces exist within a liquid.
B. Gas particles are close together.
C. Liquid molecules are close together.
D. Liquid molecules possess more kinetic energy than
gas molecules.
E. Liquid molecules move at a slower speed than gas
particles.

The answer is C. Don't know why tho

 

[vize]

for the first question, it's basically asking you which of the compounds will form a precipitate. so then, out of the choices, you want to find the best one that is least soluble in water and will thus form the precipitate. out of those choices, only A fits this criteria.

in the second question, it's easier to compress a gas to a liquid because the gas molecules are farther apart and more susceptible to compression. liquid is a more condensed phase than a gas, so it'll be more resistant to compression.

 

[keibee82]

4. Which of the following, if added to a saturated aqueous
solution of NaCl, would most effectively reduce the
chloride ion concentration?
A. AgNO3
B. Ba(NO3)2
C. K2SO4
D. H2S
E. CH3COOH

Need some help on this problem. The answer is A. Can anyone please explain to me why this is the correct answer? Thanks.

just remember the solubility rule. In this question, try to find out which of
ion can precipitate with chloride ion. Chloride is always soluble with the exception of three Ag+, Pg2+, Hg2 2+. Therefore choice A has Ag in it with
NO3 which is always soluble in the water. AgCl will precipitate and chloride
ion concentration will be reduced.

 

[allstardentist]

Thanks alot for ur responses. I get it now.